Apparatus for artificial respiration, in particular for purposes of anesthesia



Oct. 16, 1956 H. KOCH ETAL 2,766,753

APPARATUS FOR ARTIFICIAL RESPIRATION, IN

PARTICULAR FOR PURPOSES OF ANESTHESIA Filed April 15, 1954 2Sheets-Sheet l 40 6 6 INVENTORS 60 a? //v?/c/-/ A CA,

4317/. Fukavfgg,

[771?4 EMOLLE/P/NG,

0 1956 H. KOCH ETAL 2,766,753

APPARATUS FOR ARTIFICIAL RESPIRATION,. IN PARTICULAR FOR PURPOSES OFANESTHESIA Filed April 15, 1954 2 Sheets-Sheet 2 I N V E NTORE ATTORNEYS2,766,753 APPARATUS FOR ARTIFICIAL RESPIRATION, IN PARTICULAR FORPURPOSES OF ANESTHESIA Heinrich Koch, Hans Fiirniss, and Karl F.Miillering, Lubeck, Germany, assignors to Firma Dragerwerk, Heinr. 8;Bernh. Drager, Lubeck, Germany Application April 15, 1954, Serial No.423,482 7 Claims. (Cl. 128-188) The invention relates to apparatus forproducing artificial respiration, and more especially to such apparatusdesigned for anesthesia.

Known devices for this purpose have various disadvantages. In some, theexhaling step is entirely dependent on the natural collapsing action ofthe lungs. This action, both as to the volume of air exhaled and as tothe time required for exhalation, then is wholly dependent on thepatients condition at the time, and cannot be controlled by theoperator.

In some such systems, also it is necesary, in order to maintain adequaterespiration, to use a substantial minimum pressure when filling thelungs to insure a sufiicient contraction of the lungs during exhalationto produce a proper exchange of gas between the lungs and the bag. Thispressure may be too great for the patients safety. On the other hand, ifthe lungs contract too far during exhalation, excessive breathing mayoccur because the lungs are refilled to the same pressure. Such devices,therefore, do not allow proper control of the breathing, because thelungs expand only between the maximum pressure and the pressure createdby the contraction of the lung at the transition between inhaling andexhaling, so that the average breathing pressure of the lung is higherthan normal. In lung surgery, for example, it is undesirable for thelungs to fill completely when the thorax is opened.

Other respiratory devices, in which the rate of exchange is determinedby the displacement and the rate of operation of the pump, and is fixedfor any given pump, have the disadvantage that in lungs of differentsizes different pressures will be created, the smaller the lung thegreater the pressure. In order to make such a device of general utility,it is necessary either to provide means for varying the stroke of thepump which supplies the pressure or to have several interchangeablepumps of different output. Another disadvantage of such devices is thatthe maximum pressure is not adjustable from the very beginning of theoperation. Also, if the respiratory passages become temporarily blocked,because of the presence of mucus or some surgical action, the pistonwill build up a considerable pressure head in the system which may bedangerously high. Such systems may be provided with pressure reliefvalves to permit the escape of gas under such circumstances, but thisgas is then lost and must be replaced in the system when normaloperation is restored. Also, during the suction stroke of the pump,especially after the escape of gas from the system, subatmosphericpressures may be created in the lungs which are so low as to causeseepage of blood through the lining into the lung, thereby causingdamage to the lung. If a safety valve is used to avoid such excessivelylow pressure, the air drawn in will dilute the gas in the system so thatthe desired proportions of the different gases will no longer exist,especially when an anesthetic gas is being used.

The primary object of the present invention is to avoid thedisadvantages of the known systems.

Another object of the invention is to provide a respiratory system inwhich the pressure can be maintained within a desired range withoutadding gas to or allowing it to escape from the system.

A further object of the invention is to provide a system ice in whichsub-atmospheric pressures can be created with-' out the use of a pistonpump.

An additional object of the invention is to provide a system in whichthe range of pressures can easily be varied as desired.

Further objects and advantages of the invention will appear more fullyfrom the following description, especially when taken in conjunctionwith the accompanying drawings which form a part thereof.

In the drawings:

Fig. 1 shows in section a system embodying the invention;

Figs. 2 to 5 are details of parts of Fig. l; and

Figs. 6 and 7 are views of modifications of parts of Fig. 1.

In the system, the lungs 2 are connected to a fitting 4 in anyconventional manner; as by an intertracheal catheter. From this fittingrun branch pipes 6, 8, containing one-way valves 10, 12 for exhalationand inhalation respectively. These valves (see Figs. 2 and 3) arepressed on their seats by springs 14. The pressure of the springs can beadjusted by turning stems 16 threaded in the walls of the valves. Pipe 6also contains a carbon dioxide absorbing cartridge 18.

Both pipes connect to a common fitting 20 fixed in the wall 22 of achamber having a removable cover 24 which can be held in place in anysuitable manner. A respirator bag 26 is removably threaded on fitting20. Inside cover 24 is a plate 28 forming a piston whose position can beadjusted by turning its stem 30 which is threaded in the cover. Bag 26may be formed of any suitable flexible but impervious andnon-stretchable material, such as cloth impregnated with rubber. It ispreferably of bellows construction.

Enclosed in a casing 32 provided with openings such as 34 (Fig. 4) is apump mechanism which is connected with chamber 22 by a pipe 36. The pumpincludes a venturi section 33, into which air under pressure is fed fromany suitable source, such as a cylinder of compressed gas. by a valvedpipe 40, which feeds into the throat of the venturi. The pipe 36connects with a space 42 which communicates through openings 44 and 46with the lowpressure and high pressure sides of the venturi,respectively. Openings 44, 46 are controlled by valves 48, 50,respectively, mounted on opposite ends of a lever 52 pivoted at 54. Thislever is conected by a rod 56 connected to a diaphragm 58 in the wall ofspace 42. The resiliency of this diaphragm may be adjusted by turning anut 60 (Fig. 5) threaded on the end of rod 56 and engaging a spring 62which rests against a fixed frame 64.

The outlet of the venturi is closed by a check valve 66 (see Fig. 4)acted on by a spring 68 whose tension is adjustable by a stem 70threaded in the wall 32. The low pressure side is provided with anintake check valve 72 acted on by a spring 74 adjustable by a stem 76.

A valved line 78 is connected to pipe 8, or to some other point, so thatoxygen, anesthetic gas, or the like can be introduced into the system.

This arrangement operates as follows:

With the parts in the position shown in Fig. 1, valve 66 is open as isvalve 48. Air flowing through the venturi will create a suction at theintake side of the venturi, which will gradually reduce the pressure inspace 42 and thereby in chamber 22, causing bag 26 to expand and drawair from the lungs. The suction will depend on the setting of valve 66,being less as the tension of spring 68 is increased, since less air willthen flow through the venturi. Thus the rate of expansion of bag 26 canbe regulated by stem 70.

Eventually, the pressure in space 42 will become low enough to draw indiaphragm 58 in the direction of the arrow (Fig. 1). This diaphragm maybe of a snap action type. The pressure at which it is moved can bevaried by adjusting nut 69. When the diaphragm moves inward, it shiftslever 52, closing valve 43 and opening valve 50, thus admitting air fromthe pressure side of the venturi to spaces 42 and 22, and graduallycollapsing bag 26 so as to force air into the lungs. During thisoperation, the amount of air flowing through the venturi will depend onthe pressure on valve 72, and the rate at which the pressure builds upcan therefore be controlled by stem 76. The greater the tension orspring 74, the slower the pressure builds up.

When a certain pressure is reached in space 42, diaphragm 58 is pushedoutward, and the parts return to the position shown in Fig. 1.

When the respirator bag expands, it draws air from the lungs throughpipe 6, valve and absorber 18 so as to remove the carbon dioxide. Therate of this exhalation can be controlled by valve 66. When the bagcontracts, it forces air into the lungs through pipe 8 and valve 12. Therate of this inhalation can be controlled by valve 7 2.

The use of a pneumatic pump, of the type shown, makes it possible tocontrol very simply, by nut 60, the pressures produced in chamber 22 andtherefore in the respiratory system. Also, such a pump switchesautomatically and immediately from the suction to the pressure phase,and vice versa, as soon as the high and low pressure limits are reached.Thus it is impossible for excessively high or low pressures to beproduced in cham- 0 her 22.

Respirator bag 26 is removable, so that bags of diflerent sizes can beused for different patients. It is also possible to limit the expansionof bag 26 by moving plate 28 downward within chamber 22.

It may be desirable to connect a second respirator bag 80 to the fitting6 through a valve 82. This may be filled with the anesthetic gasmixture. This makes it possible to vary the inflation of the lungs asdesired. For example, opening valve 82 and collapsing bag 80 (by hand,for example) will inflate the lungs further. Expanding of bag 80 willhave the opposite effect.

In Fig. 6, the second respirator bag 84) is connected to fitting by twopipes 84, 86 which can be selectively opened by a three-way valve 88.Pipe 86 contains two adjustable check valves 90, 92 acting in oppositedirections.

With such an arrangement, if valve 92, which opens into bag 80, is 'setto open at a very slight excess over the desired maximum pressure, andif valve 88 is set so as to connect pipe 86 with fitting 20, the lung ofthe patient can be filled only up to this pressure even if the pressurein chamber 22 becomes excessive. Likewise, if valve 90, which opens outof bag 80, is set slightly below the desired minimum, the pressure inthe system cannot drop below this minimum since additional gas willenter the system from bag 80. After each such operation, the next phaseof the respiratory cycle restores the balance with bag 80.

In Fig. 7, the cover 24 carries on its lower face an inflatable bag 94which can be supplied with gas under pressure or with a liquid throughvalved pipe 96. By varying the inflation of bag 94, the amount to whichbag 26 can be inflated can be regulated.

While we have described herein some embodiments of our invention, wewish it to be understood that we do not intend to limit ourselvesthereby except within the scope of the claims hereto or hereinafterappended.

We claim:

1. Artificial respiration apparatus comprising a respirator bag, aclosed system for connecting said bag to the lungs of a patient, meansforming a chamber enclosing said bag, and means to producesuper-atmospheric and subatmospheric pressures in said chamber, saidpressure producing means including an injector pump, and check valves atthe high and low pressure sides of said pump.

2. Apparatus as claimed in claim 1, having adjustable means for limitingexpansion of said bag.

3. Artificial respiration apparatus comprising a respirator bag, aclosed system for connecting said bag to the lungs of a patient, meansforming a chamber enclosing said bag, and means to producesuper-atmospheric and sub-atmospheric pressures in said chamber, saidapparatus having adjustable means for limiting the expansion of said bagcomprising a piston-like member adjustably mounted in said chamber formovement towards and from the bag.

4. Artificial respiration apparatus comprising a respirator bag, aclosed system for connecting said bag to the lungs of a patient, meansforming a chamber enclosing said bag, and means to producesuper-atmospheric and sub-atmospheric pressures in said chamber, saidapparatus having adjustable means for limiting the expansion of said bagcomprising an inflatable member mounted in said container opposite thebag.

5. Artificial respiration apparatus comprising a respirator bag, aclosed system for connecting said bag to the lungs of a patient, meansforming a chamber enclosing said bag, and means to producesuper-atmospheric and subatmospheric pressures in said chamber, saidpressure producing means including an injector pump having a venturipassage and means to supply air under pressure to the throat of theventuri passage, and means responsive to the pressure in said chamberfor connecting the chamber to the throat of the venturi passage when thepressure in the chamber reaches a predetermined maximum and to the mouthof the venturi passage when the pressure in the chamber reaches apredetermined minimum, an inwardly opening check valve connected withthe throat of the venturi passage and an outwardly opening check valveconnected with the mouth of the venturi passage.

6. Artificial respiration apparatus comprising a respirator bag, aclosed system for connecting said bag to the lungs of a patient, meansforming a chamber enclosing said bag, and means to producesuper-atmospheric and sub-atmospheric pressures in said chamber, saidpressure producing means including an injector pump having a venturipassage and means to supply air under pressure to the throat of theventuri passage, openings from said chamber to the throat and mouth ofthe venturi passage, a pivoted lever having valves thereon forselectively closing said openings, and a diaphragm in the wall of saidchamber so connected to said lever as to move said valves to connect thechamber to the throat of the venturi passage when the pressure in thechamber reaches a predetermined maximum and to the mouth of the venturipassage when the pressure in the chamber reaches a predeterminedminimum, an inwardly opening check valve connected with the throat ofthe venturi passage and an outwardly opening check valve connected withthe mouth of the venturi passage.

7. Artificial respiration apparatus comprising a respirator bag, aclosed system for connecting said bag to the lungs of a patient, meansforming a chamber enclosing said bag, and means to producesuper-atmospheric and sub-atmospheric pressures in said chamber, saidapparatus having a member within the chamber, means mounting the memberfor movement towards and from the bag, and means to adjust the positionof the member so as to limit expansion of the bag.

References Cited in the file of this patent UNITED STATES PATENTS BleaseApr. 1, 1952

